Lexeme

A lexeme (/ˈlɛksiːm/ (listen)) is a unit of lexical meaning that exists regardless of the number of inflectional endings it may have or the number of words it may contain. It is a basic abstract unit of meaning.[1] Put more technically, a lexeme is an abstract unit of morphologicalanalysis in linguistics, that roughly corresponds to a set of forms taken by a single word. For example, in English, run, runs, ran and running are forms of the same lexeme, which we may represent as RUN.[2] A related concept is the lemma (or citation form), which is a particular form of a lexeme that is chosen by convention to represent a canonical form of a lexeme. Lemmas, being a subset of lexemes, are likewise used in dictionaries as the headwords, and other forms of a lexeme are often listed later in the entry if they are not common conjugations of that word.

A lexeme belongs to a particular syntactic category, has a certain meaning (semantic value), and in inflecting languages, has a corresponding inflectional paradigm; that is, a lexeme in many languages will have many different forms. For example, the lexeme RUN has a present third personsingular form runs, a present non-third-person singular form run (which also functions as the past participle and non-finite form), a past form ran, and a present participlerunning. (It does not include runner, runners, runnable, etc.) The use of the forms of a lexeme is governed by rules of grammar; in the case of English verbs such as RUN, these include subject-verb agreement and compound tense rules, which determine which form of a verb can be used in a given sentence.

The notion of a lexeme is very central to morphology,[3]and thus, many other notions can be defined in terms of it. For example, the difference between inflection and derivation can be stated in terms of lexemes:

^RUN is here intended to display in small caps. Software limitations may result in its display either in full-sized capitals (RUN) or in full-sized capitals of a smaller font; either is regarded as an acceptable substitute for genuine small caps.